Secondary Season Research Articles

Climatological context of the mid-November 2021 floods in the province of British Columbia, Canada

The Canadian province of British Columbia (BC) is subjected to large-scale, destructive floods. The most dramatic was a mid-November 2021 event when atmospheric rivers (ARs) linked to high-intensity storms caused heavy rainfall in southwestern BC, triggering catastrophic flooding. This study examines 37 floods from 2000 to 2021 using information from over 250 climatological stations and compares events with the mid-November 2021 flood. The dates of the floods showed a bi-modal pattern: a primary season (spring to early summer, 16 floods) and a secondary season (fall to early winter, 21 floods). Five mechanisms controlled these floods: heavy rainfall, rapid snowmelt, severe ice jam, rain-on-snow, and a mixture of snowmelt and ice jam; the mid-November 2021 flood was mainly driven by heavy rainfall. Of the 37 floods, those affected by either heavy rainfall (18 floods) or rain-on-snow (10 floods) were used to derive a relationship between the average daily precipitation amount over the duration of an event and the associated integrated water vapour transport IVT¯. Flood events showed a strong linear relationship between these variables with R2≥0.85, p < 0.05, and values of these parameters were significantly higher for the mid-November 2021 flood than for > 90% of the others, although they were not the highest. The mid-November 2021 flood was also one of the four rainfall-related floods that occurred in the secondary season with IVT‾ > 400 kg m−1 s−1. The frequency of flood events over the last five years of the study period has slightly decreased when considering flood events with unknown insured cost. In contrast, insured costs of these events have increased, suggesting that present-day floods are becoming more impactful and may require changes to flood management strategies to reduce costs.

Component sequence and thermal mass effects on the transient thermal performance of concrete walls

The increased requirements of buildings to reduce energy use have highlighted the importance of accounting for all factors that influence energy use in buildings. One consideration that requires further study in the envelope design of concrete-based wall assemblies is the placement of the thermal mass layer. In this study, two thermally massive walls, Insulated Concrete Form (ICF) and tilt-up walls, with the same thermal resistance but different sequencing of layers are investigated. In addition, a wall made of a homogeneous insulation layer with an identical thermal resistance was considered to further investigate the thermal mass effect on the potential for energy savings. Results of the numerical simulations performed using COMSOL Multiphysics® software indicate that, for the transient scenarios investigated, thermal mass can contribute to shifting and dampening peak heating and cooling loads, as well as saving energy. Also, less intense fluctuations were observed in the heat fluxes when considering the ICF wall. Energy savings during the primary seasons (i.e. winters in Montreal and summers in Miami) are found to be marginal but the existence of a thermally massive layer considerably reduced the demands during secondary seasons i.e. summers in Montreal and winters in Miami.

The Mars Dust Activity Database (MDAD): A comprehensive statistical study of dust storm sequences

A comprehensive Mars Dust Activity Database (MDAD) over 8 Mars years (MY 24, Ls = 150°to MY 32, Ls = 171°) is compiled from Mars Daily Global Maps. A total of 14,974 dust storm instances are cataloged with area >105 km2 that are visually distinguishable from the surface. A dust storm instance is identified as a dust storm member over multiple sols if storm movement can be tracked. Dust storm sequences are collections of members that have a coherent trajectory from their origination areas over three or more sols. There are 228 sequences, with 125 originating in the northern hemisphere. Sequences primarily originate in Acidalia, Utopia, and Arcadia Planitiae in the northern hemisphere and Aonia–Solis–Valles Marineris and Hellas Basin in the southern hemisphere. Many northern hemisphere originating sequences flush into the southern hemisphere. The primary season for non-global dust events occurs during Ls = 140°– 250°, with secondary seasons in Ls = 300°– 360°in the northern hemisphere and Ls = 10°– 70°in the southern hemisphere. Sequences are classified into three types. Main Member sequences have one dominant member; Continuous Development sequences have many smaller members; and Sequential Redevelopment sequences have repeating, medium-sized members. “Major” sequences have a maximum area >107 km2, influence the zonal-mean global opacity, and exhibit flushing behavior. Major sequences occur over a narrower temporal range and are distinguished from other sequences by the larger size and duration distributions of their constituent members. Major sequences have unique antecedent conditions, with steadily increasing dust storm area in the 6 preceding sols that is significantly distinct from conditions preceding minor sequences.

Modeling the seasonality of extreme coastal water levels with mixtures of circular probability density functions

Understanding when floods occur is fundamental to reducing flood risk, yet depictions of flood seasonality rarely address two key issues: multiple seasons and the periodicity of seasonal data. We analyze the timing of extreme water levels at 47 presently operational tide gages located along the US coastlines with periods of record ranging from 29 to 118 years. Because the dates of extreme water levels are naturally multimodal periodic data, we model them with weighted mixtures of circular von Mises distributions. Fitting probability density functions on the circumference of a circle allow periodicity to be handled implicitly, while mixture models provide insight into the timing and importance of the various modes in the overall distribution. To our knowledge, this is the first application of circular statistical modeling to coastal water levels. We find clear spatial patterns in extreme water level seasonality along the US coasts. Gages located on the West Coast experience their main flood season in the winter and a secondary season in the summer, while those on the East and Gulf coasts have more uniform distributions, fewer seasons, and maximum flood likelihood in the late summer. Analysis of water level after removing tides and sea level change reduces the importance of secondary and higher seasons and yields greater uniformity compared with raw water levels. Finally, peaks-over-threshold datasets reveal secondary flood seasons that are obscured in annual maxima series, which may become increasingly impactful as sea levels rise. These findings are pertinent to coastal infrastructure design, risk sharing via financial instruments, and emergency preparedness and response.

Coccidioidomycosis incidence in Arizona predicted by seasonal precipitation.

The environmental mechanisms that determine the inter-annual and seasonal variability in incidence of coccidioidomycosis are unclear. In this study, we use Arizona coccidioidomycosis case data for 1995–2006 to generate a timeseries of monthly estimates of exposure rates in Maricopa County, AZ and Pima County, AZ. We reveal a seasonal autocorrelation structure for exposure rates in both Maricopa County and Pima County which indicates that exposure rates are strongly related from the fall to the spring. An abrupt end to this autocorrelation relationship occurs near the the onset of the summer precipitation season and increasing exposure rates related to the subsequent season. The identification of the autocorrelation structure enabled us to construct a “primary” exposure season that spans August-March and a “secondary” season that spans April–June which are then used in subsequent analyses. We show that October–December precipitation is positively associated with rates of exposure for the primary exposure season in both Maricopa County (R = 0.72, p = 0.012) and Pima County (R = 0.69, p = 0.019). In addition, exposure rates during the primary exposure seasons are negatively associated with concurrent precipitation in Maricopa (R = −0.79, p = 0.004) and Pima (R = −0.64, p = 0.019), possibly due to reduced spore dispersion. These associations enabled the generation of models to estimate exposure rates for the primary exposure season. The models explain 69% (p = 0.009) and 54% (p = 0.045) of the variance in the study period for Maricopa and Pima counties, respectively. We did not find any significant predictors for exposure rates during the secondary season. This study builds on previous studies examining the causes of temporal fluctuations in coccidioidomycosis, and corroborates the “grow and blow” hypothesis.

Storage Losses in Traditional Maize Granaries in Togo

During the two years research 1983–1985 on traditional maize granaries in Togo, we studied three methods for loss assessment which are discussed by the FAO: the count and weigh method, the standard volume/weight method and the thousand-grain mass method. In general, between 80 and 90% of the overall losses were caused by insect feedings. Besides Prostephanus truncatus (Horn), the most important storage pests were Sitophilus zeamais (Motsch.), Tribolium spp. and Cathartus quadricollis (Guer.). Best results were given by the count and weigh method. The significantly highest losses of dry weight (12–13%) were found after 6 months in stored hybrids. At the same time, local varieties appeared much more adapted to traditional storage methods, exhibiting losses of only 3% under the same conditions. Lowest level of losses (< 1%) were observed in regularly smoked granaries in the mountain regions. The mean losses of dry weight during primary season were found to be 6.4% after 6 months, while after a storage period of 4 months during the secondary season, losses were as high as 8%. In Togo, P. truncatus was observed for the first time in spring 1984. Because of the different damage P. truncatus causes on corn, a newly developed sample weight method was examined in an additional test. After 6 months of observation, this dangerous pest caused serious losses up to 30.2%.